If you're into fitness, then you would obviously have heard of supplements, and what's a popular supplement? - pre-workout. That in itself shows that people purchase things to consume before their workout. Now, I'm not saying that just because supplement companies sell a pre-workout supp, that means you need something before, but its a part of the reason. If you wake up, at say, 7am, and workout at 8.30. Your body hasn't had any nutrients all night long, or morning. So if you try and workout, you will most likely feel light headed, possibly ill. Some people say you burn more fat this way, but honestly, I don't believe that. Your body needs energy to burn fat, so if you have nothing in your system, your body will use anything for fuel, including muscle tissue.
You don't want to eat a load of food before you workout, as working out on a heavy stomach could make you ill, and that's just not a good idea. But you want to have something to eat, some fast digesting protein, and some carbohydrates, preferably 30 minutes or more before you start your workout. This way your body will be fueled, and therefore it can start burning the fat and repairing muscle tissue. Think about it..... if you don't have any energy in your body because you haven't eaten for quite a while, how on earth do you plan on working out? you will be shattered at the very start! I have personally seen guys faint in the gym before, and when I've asked if they are okay, they have said its because they haven't eaten. If you're training for muscle gain, then you definitely need food, otherwise your body could be burning muscle tissue for energy, which is completely pointless when you want to build muscle.
So get some carbs and protein in you before your workout (the protein will help repair your muscles quicker) and you can always try some pre-workout supplements and see what you think. You need to find what works for you, as everyone is different, but don't listen to people that say you should workout on an empty stomach, because you shouldn't.